I think in the future all governments in the world will slowly move towards Blockchain-based financial instruments and the direction is towards the unification of one currency, namely BTC. Indeed, there are still debates here and there, but it won't be long before we all, if given a long life, will witness all of that and I won't be surprised if BTC will eventually reach 300K per coin.
Are you talking about a "One World Currency"? I hardly doubt that will happen in the future. Especially when governments can't reach a common agreement. The world is very polarized right now. This would only work in a "globalized" world. I'm certain governments will use Blockchain way beyond financial apps. But all of them agreeing to use a single currency for mainstream payments is crazy. I'd say we're still early to talk about something like this. Especially when CBDCs aren't even mainstream yet.
Believe me, things will be a lot worse by the time that happens. Privacy will be virtually non-existent. Governments will be able to control everything you do in life. Everything from medical to financial info will be "digitized" on Blockchains only governments can control. It's like having your entire life at the governments' fingerprints. This is the plan. It's just that most people aren't seeing the bigger picture. Who knows what would be of public blockchain networks (Bitcoin, Ethereum, etc) in the future?